The SCR flue gas denitration technology of Longking has combined the disc swirl flow technology with AIG ammonia injection technology, which can ensure ammonia/flue gas mixed more evenly. The special pneumatic regulating valve group was used to control ammonia flow, which has many advantages such as good linear regulatory, fast response, stable adjustment and good sealed performance. The advantages can ensure higher denitration efficiency and lower ammonia escape efficiency. This technology can achieve the following requirements: denitration efficiency is over 90%; ammonia escape efficiency below 2.5ppm, SO2/SO3 conversion rate below 1%.